The Enterosalivary Nitrate-Nitric Oxide Pathway: How Mouth Bacteria Help Control Blood Pressure
Dietary nitrate from vegetables is concentrated in saliva and reduced to nitrite by bacteria on the tongue, contributing to the body's nitric oxide — the molecule that relaxes blood vessels and lowers blood pressure. Because antibacterial mouthwash can suppress these nitrate-reducing bacteria, some studies link frequent antiseptic rinsing to higher blood pressure, a reason for caution about daily use.
Nitric oxide (NO) is a signaling molecule that acts as the body's endothelium-derived relaxing factor: it relaxes the smooth muscle of blood vessel walls, producing vasodilation and lowering blood pressure. Its cardiovascular role was significant enough to earn the 1998 Nobel Prize in Physiology or Medicine. **The oral bacteria connection.** Beyond the body's own enzymatic NO production, there is a dietary route called the enterosalivary nitrate-nitrite-nitric oxide pathway. Nitrate from vegetables (leafy greens, beetroot) is absorbed, concentrated in saliva, and then — critically — reduced to nitrite by nitrate-reducing bacteria living on the tongue. That nitrite can subsequently be converted toward nitric oxide in the body. In effect, part of the cardiovascular benefit of a nitrate-rich diet depends on having the right bacteria in the oral microbiome. **Why mouthwash matters here.** Broad-spectrum antiseptic mouthwashes (including chlorhexidine and other antibacterial rinses) do not distinguish between harmful and beneficial bacteria. By suppressing the tongue's nitrate-reducing bacteria, they can interrupt this pathway. Some studies have associated regular use of antibacterial mouthwash with disruption of these bacteria and with raised blood pressure (hypertension). The effect is one of several reasons clinicians advise against reflexive daily antiseptic rinsing in people who have no specific oral disease — the rinse may be solving a problem they don't have while interfering with a system they rely on.